GRB 091024A and the nature of ultra-long gamma-ray bursts

Journal Article · Wed Nov 20 04:00:00 EST 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/778/1/54· OSTI ID:22342018

Virgili, F. J.; Mundell, C. G.; Harrison, R.; Kobayashi, S.; Steele, I. A.; Mottram, C. J.; Clay, N. R. ^[1]; Pal'shin, V. ^[2]; Guidorzi, C. ^[3]; Margutti, R.; Chornock, R. ^[4]; Melandri, A. ^[5]; Henden, A. ^[6]; Updike, A. C. ^[7]; Cenko, S. B. ^[8]; Tanvir, N. R. ^[9]; Cucchiara, A. ^[10]; Gomboc, A. ^[11]; Levan, A. ^[12]; others, and

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1. Astrophysics Research Institute, Liverpool John Moores University, Liverpool, L3 5RF (United Kingdom)
2. Ioffe Physical Technical Institute, St. Petersburg 194021 (Russian Federation)
3. Department of Physics and Earth Sciences, University of Ferrara, Via Saragat, 1, I-44122 Ferrara (Italy)
4. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
5. INAF/Brera Astronomical Observatory, via Bianchi 46, I-23807 Merate (Italy)
6. AAVSO, 49 Bay State Road, Cambridge, MA 02138 (United States)
7. Department of Chemistry and Physics, Roger Williams University, Bristol, RI 02809 (United States)
8. Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)
9. Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom)
10. Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)
11. Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana (Slovenia)
12. Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)

We present a broadband study of gamma-ray burst (GRB) 091024A within the context of other ultra-long-duration GRBs. An unusually long burst detected by Konus-Wind (KW), Swift, and Fermi, GRB 091024A has prompt emission episodes covering ∼1300 s, accompanied by bright and highly structured optical emission captured by various rapid-response facilities, including the 2 m autonomous robotic Faulkes North and Liverpool Telescopes, KAIT, S-LOTIS, and the Sonoita Research Observatory. We also observed the burst with 8 and 10 m class telescopes and determine the redshift to be z = 1.0924 ± 0.0004. We find no correlation between the optical and γ-ray peaks and interpret the optical light curve as being of external origin, caused by the reverse and forward shock of a highly magnetized jet (R{sub B} ≈ 100-200). Low-level emission is detected throughout the near-background quiescent period between the first two emission episodes of the KW data, suggesting continued central-engine activity; we discuss the implications of this ongoing emission and its impact on the afterglow evolution and predictions. We summarize the varied sample of historical GRBs with exceptionally long durations in gamma-rays (≳1000 s) and discuss the likelihood of these events being from a separate population; we suggest ultra-long GRBs represent the tail of the duration distribution of the long GRB population.

• OSTI ID: 22342018
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 778; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
AFTERGLOW
CORRELATIONS
COSMIC GAMMA BURSTS
COVERINGS
DIAGRAMS
DISTRIBUTION
EMISSION
EVOLUTION
FORECASTING
GAMMA RADIATION
RED SHIFT
TELESCOPES
VISIBLE RADIATION